There are diseases that prevent a patient from maintaining normal control of the flow of intestinal contents in the patient's intestinal passageway, such as anal incontinence, reduced peristaltic function of the intestines and constipation of the intestines. (The term “patient” generally includes human beings, but may also include animals.
Also, the term “intestines” generally includes small bowel, large bowel, and anus (anal channel including the anal sphincter). This means that the term “intestinal passageway” includes the entire passage from the stomach to and including the anal orifice.) In particular, anal incontinence is a widespread disease and often occurs because of a malfunctioning of the anal sphincter, which causes an uncontrolled drainage of fecal matter through the anusintestinal passageway.
Several kinds of sphincter plastic surgery are used today to remedy anal incontinence, i.e disability to close the anal sphincter. There is a prior manually operated sphincter system in an initial clinical trial phase where a hydraulic sphincter system connected to an elastic reservoir (balloon) placed in the scrotum is developed. A disadvantage of this system is that thick, hard fibrosis is created around the reservoir by pump movements making the system useless sooner or later. Another disadvantage is that the use of hydraulic fluid always entails a risk of fluid leaking from the implanted hydraulic system.
Furthermore, it is a rather complicated task to manually pump the reservoir when defecation is needed. U.S. Pat. No. 5,593,443 discloses hydraulic anal sphincter under both reflex and voluntary control. An inflatable artificial sphincter with the pump system in scrotum is disclosed in U.S. Pat. No. 4,222,377.
U.S. Pat. No. 4,739,764 discloses a method for treating anal incontinence by electric stimulation of nerves connected to muscles controlling the anal sphincter. The function of the anal sphincter is affected by applying electric pulse trains on the nerves. One general prior solution to the problem of malfunctioning sphincters of a human body has been to implant an artificial sphincter that replaces a malfunctioning sphincter. A variety of artificial sphincters have been used in the past. These artificial sphincters have included cuffs, clamping elements or inflatable bands that are applied externally around the bodily organ that is connected to the malfunctioning sphincter.
For example, U.S. Pat. No. 6,074,341 discloses a mechanical device in the form of a loop member that is applied around a patient's organ to replace the missing or damaged sphincter. The loop member includes a wire which is used to constrict the organ in question to close the intestinal passageway.
A disadvantage common to all prior artificial sphincters is that hard fibrosis may form around the artificial sphincter over time and may cause malfunction of the artificial sphincter. Thus, the formed fibrosis may sooner or later become a hard fibrotic layer which may make it difficult for the artificial sphincter to work.
Another more serious disadvantage of the prior artificial sphincters if used for replacing malfunctioning anal sphincters is that the element of the artificial sphincter that constricts, clamps or restricts the intestines may injure the tissue wall of the intestines. Thus, a consequence of the element's constricting action on the intestines is that the element might erode into the intestines over time, and in a worst case, penetrate the constricted wall portion of the intestines. In addition, blood circulation in the constricted tissue wall portion of the intestines is eventually hampered by the pressure exerted by the element, so that poor blood circulation, or worse, no blood circulation results in deterioration of the constricted tissue.
One solution to prevent tissue deterioration due to poor blood circulation could be to apply two or more separately operating constricting elements along respective tissue wall portions of the intestines and operate the elements sequentially, whereby each tissue wall portion would have time to recover, i.e., restore normal blood circulation while one of the other tissue wall portions is constricted. However, an apparatus devised in accordance with this solution would have several disadvantages. First, the apparatus would require a large amount of space, making it impractical to implant. Second, the operation of the apparatus in moving the constricting elements between constricting and non-constricting positions day and night would require a large power supply. Such a large power supply would necessitate the implantation of a very large, high capacity battery and/or a sophisticated system for continuous wireless transmission of energy from outside the patient's body for frequent charging of an implanted rechargeable battery. Thus, because of its large size and high power consumption, the apparatus would be impractical or even unrealistic. Third, a sophisticated control system would be necessary to control the moving elements. Finally, such a complicated apparatus of the type described above would significantly add to the costs of treating a malfunctioning sphincter.
Another solution to the problem of malfunctioning sphincters that has been previously used has been the electric stimulation of the sphincter, to restore its normal function, i.e., the contraction and closing of its associated intestinal passageway. This solution would work where the normal sphincteric function is somewhat reduced and has not completely ceased. European patent application 1004330 A1 discloses an example of such a solution, in which electric pulses are delivered to the lower esophageal sphincter of a patient suffering from reflux disease to minimize reflux. However, the esophageal sphincter has to be continuously stimulated with electric pulses to keep it closed, except when the patient eats, which may result in a decreased stimulation effect over time. An even more serious drawback to this solution is that the continuous stimulation over time might cause tissue deterioration due to poor blood circulationintestinal passageway.
The use of electric stimula to restore the sphincteric function of a malfunctioning anal sphincter is only possible if the anal sphincter responds sufficiently to the stimula, i.e., closes the intestinal passageway of the intestines. In cases where the sphincteric function of an anal sphincter has completely ceased, or the anal sphincter has been removed from the patient's body, electric stimulation cannot be employedintestinal passageway.
Electric stimulation of intestinal organs other than anal sphincters can only insignificantly affect the flow of intestinal contents. For example, it is true that electric stimulation of the small intestine of an anal incontinent patient affects flow of intestinal contents, but could not possibly fully close the intestinal passageway, at least not by employing the necessary low stimulation intensities that are harmless to the human body.
Intestine dysfunction may also involve disability of controlling the muscle that contracts the bowels, colon or rectum to provide transportation of the content thereof. Such a disability usually causes constipation. In particular paralysed patients may suffer from constipation.